This invention relates to the production of precast concrete culvert sections which are usually installed in end-to-end alignment in the ground for directing a stream under a roadway and in place of using a bridge for spanning the stream. In the construction of such precast concrete culvert sections, it is desirable for the sections to have a configuration which effectively and efficiently utilizes the lateral forces acting on the side walls of the culvert section by the surrounding earth or soil to provide the culvert section with high strength for supporting substantial vertical loads on the top wall of the section. It is also desirable for the culvert section to have a minimum wall thickness, provide for a smooth flow of water into and through the culvert section and permit the maximum flow of water with a minimum overall height or rise of the culvert section. In addition, it is desirable for the culvert section to be constructed so that culvert sections with different spans and different heights or rises may be economically produced in order to accommodate water streams of various sizes.
Different forms of concrete culvert sections have been either proposed or made, for example, as disclosed in U.S. Pat. No. 1,412,616 and as produced by Zurn Industries, Inc. of Erie, Pa. and marketed under the trademark "BEBO". However, the culvert sections which have been previously proposed or constructed fail to provide all of the above desirable features, as apparent after studying and analyzing the culvert sections.